could detonation blow a water seal?

[Oedipus Rex]

I only ask because since my car had new intercooler and filters the other day we then dynoed it at WGT.

Whilst on the Dyno it ran real lean just before redline due to boost creep and cut.

The compression is fine, minimum reading was 8.2. However since that day I have not had a steady water level and after parking up today I came back to the car 30 mins later only to see water ****ing from the expansion bottle.

Fired it up and took the water cap off (main not AST) abd it slowly slowly started to rise until it was overflowing. Although no champagne bubbles.


Anyhow I digress. simple question, could detonation blow a water seal?

[g11ary]

I would not have thought so, as the seals are on the ends, not were you would expect detonation to occure, there is a small risk I guess that if a piece of apexi seal came off it could damage a seal while going through the engine cycle, but I would have thought unlikely. But I am Far from being an expert.

[Oedipus Rex]

apex seals are fine mate.

Its just a wierd one because I had the whole water system pressure tested when I got a new rad about a month ago and the water seals are less than 2 years old. However I am definitely losing coolant and wherever its going is invisible.

[Timrxmotors]

It is possible you have a cracked plate,where the water seal sits.Detonation could do this.

[Oedipus Rex]

Originally posted by Timrxmotors
It is possible you have a cracked plate,where the water seal sits.Detonation could do this.

great  :rolleyes:

[Oedipus Rex]

Tim mate,


would that show in a compression test?

[Carl]

It wouldn\'t show in a compression test.
Tim maybe right,or it just maybe that a water seal has let go any way or even a side plate has corroded.
Regards
Carl

[Oedipus Rex]

man if it is an internal engine problem I\'m gonna be so gutted. had it up to almost 320 at the wheels, great compression, loads of new shinies.

Please be something simple.......


time to find religion I think.

[Carl]

You could try a coolant system pressure check,that ought to give a good indication if anything is wrong.
Sometimes the fix can be as simple as changing the pressure cap on the AST tank.
Make sure it is a 0.9kg one or 13lb.
Regards
Carl

[MillSpeed]

Don\'t think so. If your motor had started detonating, it would have killed the apex seals. It only takes one or two good pops to crack a seal. What normally does the water seals is if the engine overheats or develops hot spots due to localised boiling of the coolant. This causes the rotor housings and end plates to warp, exposing the seals directly to the combustion gasses, needless to say theyt don\'t hold up long! Has your car been cooked recently? Either that or end plates/rotor housings have sufferd from corrosion like carl says. Anyways, if your water seals had gone you\'d defo see bubbles of combustion gasses rising to the surface in the filler neck. If you run her with the filler cap off, the coolant will rise due to the fact that it expands as it heats up, no problems there. Coolant can only get to the overflow tank via the AST cap, take it off and inspect the spring. Might have gotten a bit tired. Also check that the little return valve opens properly. Without that, your overflow bottle level will get higher and higher because the coolant isn\'t being drawn back into the engine as it cools.

[Oedipus Rex]

cheer MillSpeed mate, appreciate that. It didn\'t seem to make sense to me that it could have popped a water seal but hey, thought I\'d better check. It\'s definitely not cooked at all and having had a rebuild pretty recently I am also dubious about it being corosion. I did pop the AST cap off and have a look at it straight away and it looked fine, rubber seal fine spring looked ok etc. Still it is a 13 year old cap now, I\'ll go get a new one from Halfrauds and see if it makes any odds.

[MillSpeed]

Yeah, it\'ll only be about 4 or 5 spods, better than paying £18 from mazda! Well worth chaging these little buggers pretty regularly......they do let the coolant pressure drop over time, letting the boiling point of your coolant fall dangerously close to the engine\'s operating temp.

[Martiny]

Well, I think detonation could damage a water seal. The water is seal is exposed to cumbustion pressure, right?

Now, when we have detonation, we have an uncontrolled explosion, and to me that means that :
1) surely the pressure could rise higher than it would in a normal firing event.
2) the pressure could be applied in the wrong place - to places on the water seals that are not normally exposed to combustion pressure.

Please tell me if I talk bollocks ( mind you people DO on this site anyway!)  

[Carl]

Buy a genuine Mazda pressure cap,the ones from the factors never work the same.
Regards
Carl

[MillSpeed]

Originally posted by Martiny
The water is seal is exposed to cumbustion pressure, right?

Hells No! Well, not unless the rotor housings/end plates are warped. The water seals are just like giant rubber o-rings which rest in grooves machined into the rotor housings (or the end plates in early engines). If they are exposed to combustion gasses (which are at extremely high pressures) they\'ll burn through in no time.